Please, don't come during darkness or twilight. The childrens playground with the information board is situated at the back of some houses. So the owners might have some terrible ideas.

After Justus von Liebig recognised in 1840 the agricultural meaning of the potash salt as a fertilizer, the first potash factory was founded in 1861 in Stassfurt. The export of potassium salts to America started for cotton plantations and tobacco plantations, so the number of the potash minings rose during the following years.

In the time from 1905 to 1926 a mine in Oedesse was operated by the Hannoversche Kaliwerke AG in Oedesse to produce potash salt. The mine of Oedesse is situated in the western area of the salt dome of Berkhöpen.

The salt dome of Berkhöpen

The salt dome has a length of 2300 metres and a width of 1200 metres. The thickness of the potash layer was between 8 and 17.5 metres. An essential component of the potash layer are „Hard salts“, these are salt rocks which are harder than rock salt (Sodium chloride). In Oedesse the content of potash (K2O) was nearly 14.2%. The Hard salts included up to 80% of potassium chloride (KCl).

The salt layers originated before about 200 million years at the period of Zechstein, as sea water evaporated in a wide bassin, the „Zechsteinbecken“. By movements in the earth's crust the sea bed fell and new sea water streamed. At about 3000 m depth the salt repository was formed ,which strove by the pressure closer to the earth's surfaces. The salt dome of Berkhöpen was built up from the bedrock of the upper Zechstein. In further times the salt layer came close the earth's surface. But the slightly dissolvable salts on the top of the dome were flushed by the ground water. The hardly dissolvable components, clay and anhydrit plaster were remaining and forming a layer which is called by miners as "Caprock".

Mine Oedesse

The mining in Oedesse started in 1913. The highest annual production was reached in 1924 with 47,345 tonnes of raw salt. In 1926 the production was stopped. Only 11 miners remained to maintain the buildings and machines. In 1936 the whole mine was flooded by a water inleakage within 20 hours. This was the end of the mining in Oedesse.

Today ther is not much left form the former buildings. Only the mining laboratory (converted to a dwelling house) and the manager's villa are still preserved.

At the end of the children's playground you will find a information board about the mining history of Oedesse. Approx. 20 m away from this notice board you will see the fenced and covered entrance of the mine shaft. Below the coverplate the shaft will lead down to the depth of 900 m.

Following the forest path on the right side of the playground, you will reach the old mining dump. The mining dump as well as the salt ponds in fromt of it and the meadow of Schwarzwaser were lieing in a nature protection area. The area around the mining dump accommodates a vegetation which you will found only at the seashore, as for example the „Red Queller“. You will also find animals which had adapted to the salty ground.

For logging the cache, you have to answer the following questions. Some of the answers you will find on the notice board.

1) How old are the salt layers in the Oedesse area?

2) How does the miner call the sodium chloride?

3) What is the commercial relevance of the potash salt?

4) The salt occurence had beside the potash mining one more meaning for Oedesse and Oelheim. Please tell me.

5) In the salt ponds live primeval animals. What is their latin name?

6) Look for the place where the photo of the mining dump was recorded and tell me which type of tree you will find on the left side of the place.

Attention! You are moving in a nature protection area. Please stay on the forest path and the small path leading you to the place where the photo was recorded. It is not necessary and it ist not allowed to enter the area of the salt ponds and the mining dump.

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